Instant Search using Kotlin Coroutines/Flows with Single Source of Truth (SSOT)

SearchViewModel.kt

import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewModelScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.delay
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.SharingStarted
import kotlinx.coroutines.flow.StateFlow
import kotlinx.coroutines.flow.catch
import kotlinx.coroutines.flow.debounce
import kotlinx.coroutines.flow.distinctUntilChanged
import kotlinx.coroutines.flow.flatMapLatest
import kotlinx.coroutines.flow.flow
import kotlinx.coroutines.flow.flowOf
import kotlinx.coroutines.flow.flowOn
import kotlinx.coroutines.flow.stateIn
import kotlinx.coroutines.flow.update

class SearchViewModel : ViewModel() {
    private val _searchQuery = MutableStateFlow("")
    val searchQuery: StateFlow<String> = _searchQuery

    val searchResults: StateFlow<List<String>> = _searchQuery
        .debounce(300L)
        .distinctUntilChanged()
        .flatMapLatest { query ->
            if (query.isBlank()) {
                flowOf(emptyList())
            } else {
                fetchSearchResults(query)
                    .catch { emit(emptyList()) }
            }
        }
        .flowOn(Dispatchers.IO)
        .stateIn(
            scope = viewModelScope,
            started = SharingStarted.WhileSubscribed(5_000L),
            initialValue = emptyList()
        )

    fun onSearchQueryChange(query: String) {
        _searchQuery.update { query }
    }

    private fun fetchSearchResults(query: String) = flow {
        delay(3_000L)
        emit(
            listOf(
                "Result 1 for $query",
                "Result 2 for $query",
                "Result 3 for $query",
                "Result 4 for $query",
                "Result 5 for $query"
            )
        )
    }
}